1. Field of the Invention
The present invention relates to a fundus observation device, a fundus image display device and a fundus observation program for observing the state of the fundus oculi of an eye to be examined.
2. Description of the Related Art
As a fundus observation device, conventionally a fundus camera has been widely used. FIG. 42 shows one example of the appearance of a conventional fundus camera in general, and FIG. 43 shows one example of an optical system composition to be internally accommodated therein (e.g. ref. JP Patent laid-open No. 2004-350849). Furthermore, “observation” is intended to include at least a case in which photographic images are observed (observations with the naked eye may be included).
First, referring to FIG. 42, an explanation is made regarding the appearance of a conventional fundus camera 1000. This fundus camera is provided with a platform 3 mounted on a base 2 slidably in the front and rear, right and left (horizontal direction) directions. On this platform 3, an operation panel and a joystick 4 are installed for an examiner to conduct various operations.
The examiner may place the platform 3 on the base 2 to be moved freely by operating the joystick 4. On the top of the joystick, an operation button 4a is installed to be pressed down to photograph fundus oculi images.
On the base 2, a post 5 is installed standing upwards. On the post 5, a jaw rest 6 where the jaw of a patient is to be rested and an external fixation lamp 7 as a light source for fixing an eye to be examined E are provided.
On the platform 3, a main body part 8 is installed to accommodate various optical systems or control systems of the fundus camera 1000. Furthermore, the control system may be installed inside the base 2 or the platform, etc., or in an external device such as a computer, etc. connected to the fundus camera 1000.
On the side of the eye to be examined E of the main body part 8, an objective lens part 8a disposed opposite to the eye to be examined E is installed, and on the examiner side, an eyepiece part 8b is installed.
Furthermore, connected to the main body part 8 is a still camera 9 for photographing a still image of a fundus oculi of the eye to be examined E and an imaging device 10 such as a TV camera, etc. for photographing still images or moving images of a fundus oculi. The still camera 9 and the imaging device 10 are formed removably with respect to the main body part 8.
As a still camera 9, in accordance with various conditions such as the purpose of an examination or the saving method of photographed images, etc., a digital camera equipped with CCD, a film camera, an instant camera, etc. may interchangeably be used when it is appropriate. The main body part 8 is equipped with a mounting part 8c for interchangeably mounting such a still camera 9.
If the still camera 9 or the imaging device 10 is for taking digital images, the image data may be sent to and be saved in an image storing device such as a computer, etc. connected to the fundus camera 1000.
Furthermore, on the examiner's side of the main body part 8, a touch panel monitor 11 is installed. On this touch panel monitor 11, fundus images of the eye to be examined E created based on the picture signals output from the still camera 9 (a digital method thereof) or the imaging device 10 are displayed. Moreover, on the touch panel monitor 11, the xy coordinate system with the center of the screen as the origin is displayed overlapped with a fundus image, and once the screen is touched, the coordinate value corresponding to the touched position is displayed.
Next, referring to FIG. 43, a composition of an optical system of the fundus camera 1000 is described. The fundus camera 1000 is provided with an illuminating optical system 100 to light the fundus oculi Ef of an eye to be examined E, a photographing optical system 120 to guide the fundus reflection light of the illumination light to the eyepiece part 8b, a still camera 9, and an imaging device 10.
The illuminating optical system 100 comprises: a halogen lamp 101, a capacitor lens 102, a xenon lamp 103, a capacitor lens 104, an exciter filter 105 and 106, a ring transparent plate 107, a mirror 108, a liquid crystal display 109, an illumination diaphragm 110, a relay lens 111, an aperture mirror 112, and an objective lens 113.
The halogen lamp 101 is an observation light source to emit fixed light. The capacitor lens 102 is an optical element to converge the fixed light (observation illumination light) emitted by the halogen lamp 101 and evenly irradiate the eye to be examined E (fundus oculi Ef) with the observation illumination light.
The xenon lamp 103 is a photographing light source to be flushed when photographing fundus oculi Ef images. The capacitor lens 104 is an optical element to converge the flush light (photographing illumination light) emitted by the xenon lamp 103 and irradiate the fundus oculi Ef evenly with the photographing illumination light.
The exciter filters 105 and 106 are the filters to be used when fluorography of ocular fundus images of a fundus oculi Ef takes a place. The exciter filters 105 and 106 respectively are to be removable on the optical path by a drive mechanism such as a solenoid, etc. The exciter filter 105 is disposed on the optical path in the event of FAG (fluorescein angiography). Whereas, the exciter filter 106 is disposed on the optical path in the event of ICG (indocyanine green angiography). Furthermore, when color images are being photographed, both exciter filters 105 and 106 are retracted from the optical path.
The ring transparent plate 107 is disposed in a conjugating location with a pupil of the eye to be examined E, and is equipped with a ring transparent part 107a taking an optical axis of the illuminating optical system 100 as a center. The mirror 108 reflects the illumination light emitted by the halogen lamp 101 or by the xenon lamp 103 in the direction of the optical axis of the photographing optical system 120. The liquid crystal display 109 displays a fixation target (not illustrated) for fixing the eye to be examined E.
The illumination diaphragm 110 is a diaphragm member to cut a part of the illumination light for flare prevention, etc. This illumination diaphragm 110 is composed movably in the light axial direction of the illuminating optical system 100, and is thus capable of changing the illuminating region of the fundus oculi Ef.
The aperture mirror 112 is an optical element to combine an optical axis of the illuminating optical system 100 and an optical axis of the photographing optical system 120. In the center region of the aperture mirror 112 an aperture part 112a is opened. The light axis of the illuminating optical system 100 and the light axis of the photographing optical system 120 are to be crossed at a substantially central location of this aperture part 112a. The objective lens 113 is installed in the objective lens part 8a of the main body part 8.
The illuminating optical system 100 having such a composition illuminates a fundus oculi Ef in the following manner. First, the observation illumination light is output when the halogen lamp 101 is lit during fundus observation. This observation illumination light irradiates the ring transparent plate 107 through the capacitor lenses 102 and 104. The light passed through the ring transparent part 107a of the ring transparent plate 107 is reflected by the mirror 108 and is reflected along the optical axial direction of the photographing optical system 120 due to the aperture mirror 108 through the liquid crystal display 109, the illumination diaphragm 110 and the relay lens 111, then is converged by the objective lens 113, to be made incident onto the eye to be examined E, and illuminates the fundus oculi Ef.
Then, the ring transparent plate 107 is disposed in a conjugating location with the pupil of the eye to be examined E, and on the pupil a ring shaped image of the entering observation illumination light is formed. The fundus reflection light of the entered observation illumination light is to be emitted from the eye to be examined E through a central dark part of the ring image on the pupil.
On the other hand, when photographing the fundus oculi Ef, flush light is emitted from the xenon lamp 103 and the photographing illumination light is irradiated onto the fundus oculi Ef through the same path. In the event of photofluographing, either the exciter filter 105 or the exciter filter 106 is disposed selectively on the optical path depending on whether FAG photographing or ICG photographing is required.
Whereas, photographing optical system 120 comprises: an objective lens 113, an aperture mirror 112 (an aperture part 112a thereof), a photographing diaphragm 121, a barrier filter 122 and 123, a variable magnifying lens 124, a relay lens 125, a photographing lens 126, a quick return mirror 127 and a photographing media 9a. Furthermore, the photographing media 9a is a photographing media (CCD, camera film, instant film, etc.) of a still camera 9.
The fundus reflection light of the illumination light emitted through the central dart part of the ring shaped image center formed on the pupil of the eye to be examined E, enters the photographing diaphragm 121 through the aperture part 112a of the aperture mirror 112. The aperture mirror 112 reflects cornea reflection light of the illumination light and acts so as not to mix the cornea reflection light into the fundus reflection light made incident onto the photographing diaphragm 121. As a result, the generation of flare on the observation images or photographic images is prevented.
The photographing diaphragm 121 is a plate shaped member at which a plurality of circular light transparent parts of different sizes are formed. A plurality of the light transparent parts constitutes different diaphragms with different diaphragm values (F value), and are to be disposed alternatively on the optical path by a drive mechanism not illustrated herein.
The barrier filters 122 and 123 are to be removable on the optical path by a drive mechanism such as a solenoid, etc. In the event of FAG photographing, the barrier filter 122 is disposed on the optical path while in the event of ICG photographing the barrier filter 123 is inserted onto the optical path. Furthermore, when taking color images the barrier filters 122 and 123 are to be retracted from the optical path.
The variable magnifying lens 124 is to be movable in the light axial direction of the photographing optical system 120 by a drive mechanism not illustrated herein. This makes it possible to change the magnifying ratio of an observation and the magnifying ratio in photographing, and to focus images of a fundus oculi. The photographing lens 126 is a lens to form an image of the fundus reflection light from an eye to be examined E on the photographing media 9a. 
The quick return mirror 127 is disposed rotatably around a rotary shaft 127a by a drive mechanism not illustrated herein. In the event of photographing a fundus oculi Ef with the still camera 9, the fundus reflection light is supposed to be guided to the photographing media 9a by springing up the quick return mirror 127 that is obliquely mounted on the optical path. Whereas, in the event of photographing a fundus oculi with an imaging device 10 or of observing the fundus oculi with the naked eye of the examiner, the quick return mirror 127 is to be obliquely mounted on the optical path to upwardly reflect the fundus reflection light.
The photographing optical system 120 is further provided with a field lens (eye vision lens) 128 for guiding the fundus reflection light reflected by the quick return mirror 127, a switching mirror 129, an eyepiece 130, a relay lens 131, a reflection mirror 132, a photographing lens 133 and an image pick up element 10a. The image pick up element 10a is an image pick up element such as CCD, etc. installed internally in the imaging device 10. On the touch panel monitor 11 a fundus oculi image Ef′ photographed by the image pick up element 10a is be displayed.
The switching mirror 129 is to be rotatable around the rotary shaft 129a as well as the quick return mirror 127. This switching mirror 129 is obliquely disposed on the optical path during observation with the naked eye and guides reflected light on the fundus oculi to the eyepiece 130.
Furthermore, when a fundus image is photographed by the imaging device 10, the switching mirror 129 is retracted from the optical path. The fundus reflection light forms an image on the image pick up element 10a through the relay lens 131, the mirror 132, the photographing lens 133 and then the fundus image Ef′ is be displayed on the touch panel monitor 11.
Such a fundus camera 1000 is a fundus observation apparatus to be used for observing the state of the surface of a fundus oculi Ef, that is, the retina. Whereas, in the deep layer of retina tissues such as where the choroidea or sclera are found, in recent years, devices for observing these deep layer tissues have been practically implemented (e.g. ref JP Patent laid-open No. 2003-000543 and JP Patent Application No. 2004-52195)
The fundus observation apparatus disclosed in JP Patent laid-open No. 2003-000543 and JP Patent Application No. 2004-52195 are devices to which so called OCT (Optical Coherence Tomography) technology is applied. With such fundus observation devices, low coherence light is split into two, one of which (signal light) is guided to a fundus oculi and the other one (reference light) is guided to a given reference object, while at the same time this is a device to form a tomographic image of the surface and the deep layer tissue of a fundus oculi, based on the interference light obtained by overlaying the signal light that has passed through the fundus oculi and the reference light that has been reflected by the reference object
In order to capture the state of a fundus oculi (presence/absence of a disease or the progressing state, the degree of a therapy effect or a recovery state, etc.) in detail, it is desirable to consider both the state of fundus surface (retina) and the state of deep layer tissues (choroidea or sclera). However, by just observing an image of the fundus surface obtained from a fundus camera, it is difficult to capture the state of the deep layer tissues in detail, while, with tomographic images of the fundus oculi obtained from an optical image measuring device, it was difficult to capture the detailed state of the fundus surface or the entire retina.
Furthermore, in order to determine the state of fundus oculi comprehensively, it is considered to be desirable to determine the state of a disease by taking both the state of the retina and the state of deep layer tissues into consideration.
For that purpose, it is necessary to present a fundus image from a fundus camera and a fundus image from an optical image measuring device in a mutually comparable display manner. For example, it is desirable to make an attempt to make comparisons easier by presenting both fundus images at the same time.
Furthermore, it is desirable to be able to perform comparisons easily by adopting a display method capable of capturing the interrelationship between the fundus image from a fundus camera and the fundus image from an optical image measuring device.
Particularly, when an attention area such as a diseased part in one of the fundus images is discovered, there may be many cases in which one wishes to capture more details of the state of the attention area by referring to the state of the attention area of the other fundus images.
However, with the conventional fundus observation device, it was difficult to capture the state of the attention area in detail, as the positional relation to each other between a 2-dimensional surface image of the fundus of an eye to be examined by a fundus camera and a tomographic image of the fundus by an optical image measuring device was not easy to capture.
The present invention has been conducted in order to solve such a problematic point, and with the purpose of providing a fundus observation device, a fundus image display device, and a fundus observation program capable of easily capturing the positional relation between a plurality of fundus images, particularly the positional relation between the 2-dimensional image and the tomographic image of the surface of a fundus oculi.